The present invention relates to spring devices having a flexible wall, and more particularly, to pneumatic spring devices with flexible rubber walls for use in land vehicles as energy absorbing means.
Pneumatic springs, commonly referred to as air springs, have been used for motor vehicles for a number of years to provide cushioning between moveable parts in the vehicle. Air springs absorb shock loads impressed on the vehicle axles by the wheels striking an object in the road or falling into a depression. An air spring typically consists of a flexible rubber sleeve, also called a bellows or a bladder. The sleeve contains a supply of compressed fluid and has one or more pistons located therein or thereunder. An end cap closes off the upper region of the sleeve. During use, the piston moves axially toward and away from the end cap so as to alternatingly compress and expand the volume within the sleeve. In this manner, the air spring acts as an energy absorbing means for the vehicle.
In known air spring arrangements, there are numerous components attached to the end cap. One set of components is used to fill and refill fluid pressure within the sleeve. Another set is used to attach the air spring to the vehicle frame; another set is used to regulate fluid pressure between air springs. Such systems are effective, but are difficult to assemble and maintain due to their numerous parts. Thus, a need exists for an improved vehicle air spring that is easier to assemble and maintain, preferably by having fewer parts. The present invention is directed to fulfilling these needs and others, as described below.
In accordance with aspects of the present invention, an air spring is provided for use in a motor vehicle. The air spring includes a flexible air bladder, a support unit connected to lower portions of the bladder, and a unitary integrated top assembly connected to upper portions of the bladder. The top assembly includes a lateral shelf, a sealed body having an interior open volume and various attachment components positioned on the body for use in connecting the top assembly to the main frame. The top assembly is connected to the bladder in an airtight manner so as to accommodate a pressure within the air spring.
In accordance with other aspects of the invention, an optional connection port may be provided in the top assembly body for pneumatic communication with other air springs. In one embodiment, the top assembly body is formed in the shape of a half cone with a curved surface and an upright surface and a connection port is formed as a rigid arm extending outward from the body upright surface. In addition, an optional fill port may be provided in the top assembly to connect with a ride height system. During use, the ride height system uses the fill port to regulate the air pressure within the air springs to adjust to applied loads.
In accordance with further aspects of the invention, the top assembly body optionally includes a number of internal support ribs. In one embodiment, the internal support ribs are upright walls oriented front to back and in parallel relation to one another. Such internal support structures aide in the transmission of external loads to the mounting surface. In one embodiment, the unitary integrated top of the air spring is formed to increase the internal volume of compressible fluid in addition to the bladder volume, and to maintain an internal pressure in the range between, but not limited to, about 15 psi to about 150 psi. In another embodiment, the internal pressure is equal to or greater than 150 psi.
In accordance with still other aspects of the invention, the top assembly is formed from an injection molded plastic. Alternatively, the top assembly may be formed from a metal casting or by other unitary means.